Method, apparatus and product for manufacturing separable stairs



P. N. SlTTON June 7, 1960 METHOD, APPARATUS AND PRODUCT FOR MANUFACTURING SEPARABLE STAIRS 3 Sheets-Sheet 1 Filed March 29, 1956 FIG-2 INVENTOR. PHIKLIP N. slTToN BY *Tm/W Fal-W ATTORNEYS June 7, 1.960 P. N. S11-TON 2,939,309

METHOD, APPARATUS AND PRODUCT FOR MANUFACTURING SEPARABLE STAIRS Filed March 29, 195e 3 sheets-sheet 2 1N V EN TOR.

PHILIP N. SITTON BY Mm ATTORNEYS P. N. SITTON June 7, 1960 METHOD, APPARATUS AND PRODUCT FOR MANUFACTURING SEPARABLE STAIRS Filed March 29, 1956 3 Sheets-Sheet 3 JNVENToR. PHI/ IP N. 5l TTON States METHOD, APPARATUS AND PRODUCT FOR MANUFACTURING SEPARABLE STAIRS,

Philip N. sinon, Dayton, ohio, signor to Sanitary Plastics, Inc., Dayton, Ohio, a corporation of Delaware Filed Mai. .29, 1956, ser. No. 574,651

z claims. (ci. 12-96) Aiarent arrangement in `which the steps, according to the vFigure 5 structure, can be poured; and

Figure 7 isa sectional View indicated by line 7--7 on Figure 6 showing the manner in which the ends of the steps are'iformed in the mold, and also showing the con nection tothe mold of a Vibratorfor compacting the casting material supplied to the mold.

Referring to the drawings somewhat more in detail, a step. arrangement according to the present invention comprises opposite side members 10 land 12, a front riser member 14 and a rear member 16. The aforementioned members form the outer framework of the assembly and `serve to support the treads of the steps which iare indicated at 18, 20, 22 and 24. At the rear of each step, except the last, kare the riser members 26, 28 and 30.

z ,Reference to 'Fignires 2, 3`1and 4 will'show that the fabricated of wood if they 'are located insidethe stru'cture or if the structure is of a temporary nature', but permanent external steps mustgenerally be -constructed of concrete or of some other material which will withstand weather in order to give a sufficiently. long life.

Concrete steps Iare generally satisfactory when constructed properly, but are expensive and heavy and require the setting of forms 4and the pouring and finishing of the concrete and are, in general, quite troublesome in many cases. f

In theevent of there beingzarvfll in the region where the steps are to bel placed concrete steps quite often sink into the ground because of their Weight, and when this occurs it is quite difficult andVY sometimes practically impossible to restore the steps to their proper'position. Having the foregoing in mind, it is a primaryv object ofthe present invention to provide a prefabricated step structure which avoids the drawbacks referred to above. A still further object of the present invention is the provision of a lightweight Prefabricated step` structure which'can` be usedin substantially any location where steps are to be employed.

Aparticular object of the present invention is the provision of a plastic cast section step structure which can be integrally bonded together at the time of erection, thereby preventing the step from becoming disassembled for any reason.

A still further object of the present invention is the provision of la prefabricated step which has suicient strength for all purposes, but which at the same time is light and easily installed and which has a certain vamount of inherent flexibility that will prevent it from cracking should the ground supporting itshift somewhat.

These and other objects `and advantages of this invention will become more apparent upon reference to the following specification taken in connection `with the raccompanying drawings, in which: Y

Figure 1 is a .perspective View showing a step structurev according to the present invention;

Figure2 is a sectional view indicated by line 2-2 on Figure l;

Figure 3 is a perspective view similar to Figure l but with parts of the structure broken away to show the manner in whichthe Various parts of the step interiit;

Figure 4 is an exploded perspective View looking up from beneath the step structure showing the several parts making up a typical step assembly;

Figure 5 is a perspective View showing a modified construction wherein the tread andriser are poured as a Figure 6 is a perspective view of one type of mold side members 10 andr12 comprise the forwardly directed cleatsV 32 :and 34, respectively, which form pockets or slots adapted for receiving the tongues 36 and 38 that project rearwardly from the foremost riser member 14.

Similarly,.at'their rear ends the members 10 and 12 com-prise the backwardly facingc-leats 40 |and 42 that form slots or grooves to receivethe forwardly facing tongues 44,'and 46 formed on the back member 16. The

tongueland groove arrangements ydescribed provide means Y for aligning and locating the step parts and for transmitting stresses therebetween.v According to a preferred form of my invention, the steps may be constructed of a resin, such :as polyester resin, and when the parts of the steps are assembled, a solution of polyester resin and a solvent therefor can be utilize-dias `an adhesive for securingthe parts together.

After the frame comprising members 10, 12, 14 and 16 having been lassembled on a suitable at support and with the .said members' preferably supported until the adhesive sets, the treads and risers can be put in place. As will be seen in Figure 4, each of the risers 26, 28 and 30 has a foot portion thereon as at 48 adapted for being received in the notches Si) in the side members 10 and i2. As shown in Figure 3, these notches or recesses are of a size and shape as snugly to receive the ends of the foot port-ions. Thus, the lower edge of each riser is firmly but detachably locked in position to increase the rigidity of the stair construction las a whole. Y

Each riser, with the adjacent portion of the side members 10 and 12 forms a three-sided upstanding edge configuration for engaging beneath the periphery of the tread thereabove while th-e foot portion 48 of each riser support-ingly engages beneath the rear edge of the-next preceding step. Y

For locating the treads on the said upstanding edge, each step is formed with a downwardly opening groove 52 extending across the front edge and down the sides y of the pertaining step. When this groove is engaged by the upstanding edge previously referred to, the treads and frame are interlocked in a fixed position. Therear edges ofthe dependent original portions of they treads, indicated at 54, overlie the ends of the feet 48 on the bottoms of the risers and thus the risers also are xedly located in the assembly when the treads are put in position. v

When the treads and risers are constructed cf a resinous material, they may be cemented in position so that when the cement sets, the entire structure'will be integrally bonded together. Y p

It will be apparent that the structure can also be constructed of other materials than `plastic and concreteis one of the materials which would be satisfactory vfor-this the lower tensile strength thereof, it would be preferable foral] of the sections to be considerably thicker thanA Avr.Figure 7, vand ywhich has been described as vibrating the illustrated in the drawings if this material is employed.

Y could be employed to seal interengaging or-abutting sur'- faces, and in this manner'a substantially Huid-tightrstructure would result. c f l Y yIn any case, regardless of thev materialVV used,. Iand whether or not the parts of the assembly arecemented 'ffl together, a light but extremely strong'step' assembly is had which can be cast under controlled lfactory conditions and then 'quickly and easily assembled on `the job site.

Y AIt will-be apparent that'the particnlar size and-style of the assembly is subject to modification according to YindividualV preference, and it Will,'therefore, be appreciated'` that the showings in the drawings are purely-by way-of example Aandare intended only to represent one modified Y form which the 'present invention' can take.VVV n UThe-stair structurel-shown in `Figure 5 comprises integral treads and risers. The tread portion`60 and riser.

portion 62 are cast-.integrally together lwith a ange64- at-.thefront edge of the step extending acrossthe frontof v the sides of each tread embracing the top outside edge of Vthe side members 68.YV Each tread-riser combination-may .also `have Va ange .V70 along the rear edgeY engagingV the sides -of the side members 68. -f f y {'A'ccording vtoctlriermodification of VFigure 5 thevtreads and risersare advantageouslyV cast as a 'single element in one operation-by availingof a mold of the nature illus- Ytrated in Figures 6 and 7. -This'mold comprises a lower V the preceding riser, and with a dependent ange66 valong portion' 72-having`hinged'thereto the cover portions 74 at 78, in which the 'material can be cast in the mold.`

and 7761 that Ydefine the confines within whichY the treads Y Y Yand risers are cast. These *portionsV of theV mold meet while leavingY a pouring opening of substantial Vsize,' as

Y vThe advantage of casting the-treads and risers in the of eliminating 'all airrbubbles and the like on the exposed surfaces of the treated steps or risers so that a perfectly.

. smooth finish Vwill be'had;.or, in case one of the surfaces Vis figured, asurface that will correspond exactly with the corresponding surface of the mold.

Y The arrangement of the mold riser at 78, Vwhen the ymold is supplied witha Vslight exess of material, results in a-stiffening rib 80 across the reark edge of the tread 60, thereby making for an extremely Vstrong construction. As will be seen in Figure 7 the rib 80Y is interrupted f adjacent the side edges of the tread so asY nottointerfere with the inter-fitting of the tread with the Vside membersY 68.

Figure v7 Ywill also reveal a vibrator 82 for vibrating f "the mold during the Vfilling thereof which greatly facilitatesjthe compactingof the material within the moldv and eliminates air bubbles and distributes'the material in themold.

YIt has been mentioned that various materials can be used according to thisY invention and among these materials is concrete, also polyester resin having various fillers therein, suchas ground organic material, crushed or powdered stone and the like. Y

Ittwi'll be understood that'theeomposition fromwhich l the steps are constructed is inherently of anacid-resisting ,'nature, particularly -when constructed of polyester resin,

and it; has good Weather-resisting properties. The steps,

, when Vmade ofV plastic material, would haveY stillV further i characteristics of` meriti-because saltV and likede-icing materials couldV be put on the Vsteps without damaging vibrator 82A referred to Yabove andillustrated in Yinverted manner illustrated in Figure 6 is for Vthe purpose mold, can be a device that -variesconsiderably in frequency. For relatively heavy viscous materials that dow only slowly it is conceivable that satisfactory results might be obtained from merely bumping the mold at fairly infrequent intervals, say, `once every half minute, which would promote the flow. of the material into the far reacheseof-the mold cavity. r-

Onltvhfefotherihand, certaiuother matters, such vas those which might tend to permit airbubbles to cling to the surface, probably would be preferable to increase the frequency of the -vibration substantially even up to three hundred thousand cycles per second, which is about the limit of whatisgenerallygconsidered to be the supersonic range. "Y

The preferred material has been described as consisting of polyester resin having various llers therein. It will be understood that, in addition to the ground organic material which has been mentioned, inorganic material as Well could be 'employedy orY acombination thereof.Y In anyfcase, this material would either b e ground Vor granulated to a sufficient degree such Ythat the mixture thereof with theresinous material would form a readily ilowable composition.,ir The material could also include dyes or pigments in ordertimpart 'color to the finished product, ifsodesired.V Y' t It has been' mentioned'above that one portion of the mold might have a patternV thereon. This pattern would i' pleted, either by machining the tread surface, or by otherwise-'forming the said surface, or by adhering thereto by Ya'suitable cement, a'thin-sheet of suitably wear-resistant material having the desired A configuration thereon. Y VIt will be understood AthatV this invention is susceptible to modification in order to adapt vit to diierent usages and conditions, and accordingly it is desired to comprehend suchmodications within this invention as may fall Within the scope ofi' the appended claims. Y I Iclaim y A c 1. Inr a prefabricated stairfstructure; 'side members, front and back members, risermembers and tread members all preformed of castable material, said side members and front andpback4 members having interengageable elements of'a tongue and groove interlock thereon, said side members being notched to Vform Stringer means,rsaid riser .Y

members being fitted against the vertical portions of the K notches in the side members; said-riser members extending-from the outside limit of one side member to the outside limit of the other thereof and eachA riser member having a forwardly projecting foot extending across the entire width Vthereof atthe bottom, Ysaid notches in theside members being notched attheir bottom corners snugly to receive Ithesaid feet, and each tread member havingran outer dependent peripheral flange extending across the front and down theV sides to t outside the next preceding' riser member and along thegsides of the side members and to embrace the ends of the foot on thepnext succeeding riser member, each tread portion alsoV comprising a second dependent flange located inwardly of-said peripheral ange and engaging the inside surfaces of'the preceding riser member and the said Yside members.

2. In a Vprefabricated 'stair structure, side members, front and back members, riser members and tread Vinembers, all ofrsaid members being precast and comprising substantially at members Vwhereby the 'knock down stair structure can readilybe''packaged in smallspace for-.storage or shipment, said side and front and back members being adapted for being placed in a'vertical position with their ends thereofinengageme'nt, there'being @inter-'engageable elements of a tongue )and groove. interlock on bers and embracing the ends of the foot of the next riser member, each tread portion also having a second ange engaging the inside surfaces of the preceding riser membei' and the insides of the said side members. 

